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E-cigarettes are in the news again. This time with headlines that they may cause cancer.

But the study that the stories are based on, published in the journal PNAS, doesn’t show this.

What did the study do?

Researchers from New York University School of Medicine looked at how e-cigarette vapour affected the DNA of mice, and human cells in a dish.

They didn’t look at how it affected people. And they didn’t directly compare it to smoking.

The researchers focused on how components of e-cig vapour damage cells’ DNA. And DNA damage increases the risk of cancer.

But they didn’t look directly at whether e-cigs caused cancer, either in mice or in people.

What did the study show?

They found that e-cig vapour raised levels of DNA damage in the lungs, bladders and hearts of mice.

They also found that the molecular machinery cells use to repair this DNA damage was less effective in the lungs of mice exposed to e-cig vapour.

Then they looked at how nicotine, the chemical that e-cigs vaporise, affects human lung and bladder cells grown in a lab dish. Nicotine is what makes cigarettes addictive, but isn’t what causes the damage from smoking. Both e-cigarettes and conventional cigarettes contain nicotine, but e-cigs have much lower levels of the harmful components of tobacco smoke.

The researchers found that nicotine damages the DNA inside those lab-grown human lung and bladder cells. And they found that these cells were less able to repair this damage. These cells were then more susceptible to further genetic faults that could give them properties like those of cancer cells.

What do the results mean?

The researchers described their results with an interesting line:

“It is therefore possible that e-cigarette smoke may contribute to lung and bladder cancer, as well as heart disease, in humans.”

While this is technically possible, the study didn’t look at humans, and so didn’t show any effect on the health of humans.

Different e-cigs devices deliver different amounts of vapour, and people use them in different ways. So the levels of e-cig vapour and nicotine used in the study might not match the levels that people are exposed to through normal use.

And other research didn’t show a link between nicotine products and cancer.

Finally and crucially, the study didn’t compare vaping to tobacco smoke.

What now?

The evidence so far shows that e-cigarettes are far less harmful than smoking.

And for some people they’re a helpful aide to stop smoking.

Up to two-thirds of long term smokers will die because of their addiction. E-cigarettes don’t contain tobacco, which is the biggest cause of preventable death worldwide.

E-cigs are a relatively new technology and so we can’t be certain about any long-term effects the devices might cause to health – they haven’t been around long enough for this to be completely worked out. But compared to smoking, the evidence so far shows they are less harmful.

Studies like this are important for building up the evidence around vaping, and how e-cig vapour might damage cells in controlled conditions. It’s a small piece in the puzzle, and must be viewed alongside other studies. Large, long-term studies are also needed to definitively answer health questions, because those conclusions can’t be made from lab-grown cells and mice alone.

The popularity of e-cigs continues to grow, but figures show that most people using these devices are now ex-smokers, and people mainly use them to quit smoking or cut down.

So conclusions around the health effects of vaping must be viewed alongside the damage that smoking has wreaked for decades. Only then can smokers make a call that could have a big impact on their health.


If you want to quit smoking you can find support to help you here, and find out about your local Stop Smoking Services here.


Philippe Dodier July 2, 2018

Thanks a lot for sharing the news.

Dayle June 25, 2018

l think i wanna marry you

Blaine D. June 7, 2018

I’ve used a JUUL now for about 5 weeks. I intended to cut one in every 4 cigs by using it. I’ve been a 2-3 pack a day smoker for 10 years and a 1-2 pack a day for almost 20 years before that. I haven’t touched a cig at all in 3 weeks.

I went to the local track yesterday to see if my lungs have improved. Last year at this time after 30 days training I could run 1.5miles and with no training or preparation I ran 2.25miles yesterday. My smokers cough has pretty much gone away completely and I barely use my inhalers that I used to need 3-5x per day. I’ll take my chances with my JUUL.

Previously I’ve used other vape machines and e-cigs and had results that varied, including residue build up in my mouth and more trouble breathing than when smoking.

I believe that the type of vape/e-cig and liquid makes a huge difference and should be studied or factored in.

JEO June 3, 2018

I’m an ex-smoker…since vaping was invented. E-cigarettes have definitely saved my life. My sincerest thanks to this tech!

Jordan May 9, 2018

You’ve claimed that the study didn’t show that vaping can contribute to cancer risk in animal models…. But it does show that. Rather directly, in fact. Mice are 85% identical to humans when it comes to coding regions in their genome. Because of this, they’re a viable model for studying some human disease processes.

Speaking Truth April 18, 2018

I’ve poisoned myself for 25 years by smoking on the coffin nails and can tell you first hand when I started vaping 6 years ago it was God sent! I could see/smell/taste/breathe/feel much better within the first 2 weeks of switching to vaping. Its ridiculous how the big tobacco greedy companies haven’t had enough money made by contribution to human skulls and skeletons and continue paying off some “unknown lobbyists” to publish all the scare tactics of articles to deter people from longevity and quality of life just so they can make all the $$ and make us people sick and pass us on to the big pharma to continue making $$ by radiation/so called treatments and finally pass us in to the grave (population control). Guess what? Go screw yourselves big pharma and tobacco! People are getting wiser and you’re losing the war!

Ben March 29, 2018

Hi Michael,
Thank you for writing this article. I am personally doing a research on vaping and your post is helpful. I look forward to reading more of your posts. Cheers!

Mawsley February 12, 2018

Aryeh Greenberg’s link is precisely the kind of ridiculous, pseudo-research that places the lives of a billion smokers at risk. Place cultured cells in a dish in contact with any substance and they will die – which, of course, is just the response the researchers sought. It is shameful that the media gives wide coverage to junk science like this and ignores proper studies. Greenberg clearly doesn’t value harm reduction for smokers – fortunately for us in Britain our NHS and medical bodies do.

Trisha February 5, 2018

I’ve been using ecig for around 6-7 months now, and feel so much better for it. I try to keep up to date with all the research and studies, though this one doesn’t seem as reliable as most. I’m in the process of cutting out nicotine (in stages, almost there…) as I believe the chemical is harmful as well as addictive, which this study also seems to suggest, however a nicotine free ecig study alongside the standard nicotine levels being studied on the mice and human tissue would make an interesting and maybe more informative read.

B February 4, 2018

This doesn’t tell us anything. I thought it was half of smokers not 2/3.